Ultraviolet light absorbing compounds, silicone compositions and methods for making same

ABSTRACT

An ultraviolet light absorbing silicone composition is disclosed which comprises silicone base polymer and ultraviolet light absorbing component present as, or derived from, one or more silicon-containing ultraviolet light absorbing benzotriazole derivatives. Also disclosed are methods for producing such silicone compositions and derivatives. Such silicone compositions, which are preferably optically clear, are useful as lens materials.

RELATED APPLICATION

This application is a division of application Ser. No. 07/969,912, filedNov. 2, 1992, now U.S. Pat. No. 5,352,753 which, in turn, is acontinuation-in-part of application Ser. No. 07/691,149, filed Apr. 25,1991, now U.S. Pat. No. 5,164,462, and a continuation-in-part ofapplication Ser. No. 07/959,394 filed Oct. 9, 1992, now U.S. Pat. No.5,376,737 each of which applications is incorporated in its entirety byreference herein.

BACKGROUND OF THE INVENTION

This invention relates to ultraviolet (UV) light absorbing compounds,polymer compositions and methods for making same. More particularly, theinvention relates to UV light absorbing compounds and to polymercompositions including silicone polymers which compositions include, orare partially derived from, such UV light absorbing compounds, and tomethods for producing such UV light absorbing compounds and polymercompositions. The subject polymer compositions, which are preferablyoptically clear, may be used in the fabrication of UV light absorbingocular devices such as corneal contact lenses, intraocular lenses, andcorneal intrastromal implant lenses.

The incident light entering the eye is composed of the entire spectrumof wavelengths including the ultraviolet, visible, and infrared. Thecornea preferentially filters UV light in the range of about 300 nm toabout 400 nm. Thus, in the eye with its natural lens in place relativelylittle radiation of wavelengths less that about 400 nm reaches theposterior intraocular structures, e.g., the vitreous humor and theretina.

In the aphakic individual, i.e., that individual who has had the naturalcrystalline lens removed, there is a loss in protection for the retinafrom UV light in the above-noted range. Thus, the use of UV lightabsorbing contact or intraocular lenses is particularly important forthe aphakic person. It is further believed that UV light screeningspectacles or contact lenses may retard the development of a cataract inthe natural lens.

Although low molecular weight, non-polymerizable UV light absorbingcompounds of various types are effective in blocking UV radiation whencompounded into polymer formulations, their extractability in variousmedia may limit their utility. Also, such UV light absorbing compoundshave a potential for phase separation from the polymer formulation. Thisso-called "blooming" effect is dependent on how soluble the UV lightabsorbing compound is in the polymer. These problems are remedied by thesynthesis of polymerizable, UV light absorbing monomers which can becovalently coupled into the polymer matrix. These covalently bonded UVlight absorbing monomers are not extractable and do not phase separatefrom the remainder of the polymer. Articles fabricated from UV lightabsorbing silicone compositions incorporating these polymerizable UVlight absorbing monomers therefore maintain stable ultraviolet screeningcharacteristics and do not exhibit haze or blooming. The "blooming"problem could be solved by providing a UV light absorbing compoundwhich, even though it is not polymerizable, has increased solubility inthe polymer.

Reich, et al U.S. Pat. No. 4,868,251 discloses UV light absorbingcompositions comprising silicone elastomers and, covalently bondedthereto, a UV light absorbing component derived from one or more ofcertain vinyl functional benzotriazole monomers. In preparing the finalcomposition, heat and/or a co-solvent, such as isopropanol, is oftenneeded to dissolve the UV light absorbing monomer in the siliconeprepolymer. It would be advantageous to provide a UV light absorbingcomponent which has substantial compatibility or solubility in thesolvent. This would simplify, ease and quicken the manufacture of thefinal UV light absorbing polymeric composition. Further, an UV lightabsorbing component with enhanced compatibility and/or solubility wouldresult in a monomer/prepolymer mix with a relatively long shelf life sothat the mix could be produced and stored well before its ultimate usewith little or no phase separation or other detrimental effect.

European Patent Publication No. 0282294 discloses vinylsilylalkoxyarylbenzotriazole monomers which are incorporated into optically clearsilicone polymers. These silicon-containing monomers are taught as beingmore reactable with the silicone polymers than arenon-silicon-containing monomers so that a more complete reaction andless non-reacted monomer are obtained. This publication still disclosesthe need for relatively high temperature, on the order of 90° C., tosolubilize the monomer in the silicone prepolymer. Because of theseelevated temperatures, the monomer is often mixed with only one portionor part of a conventional two part silicone formulation. The resultingadditional mixing step adds to the cost and complexity of the finalpolymeric composition manufacturing process. Also, the limitedsolubility of this monomer reduces the effective shelf life of theprepolymer/monomer mixture.

Clearly, it would be advantageous to provide a new, preferably moresoluble, class of UV light absorbing compounds, particularly for use insilicone polymers.

SUMMARY OF THE INVENTION

New UV light absorbing compositions and compounds and methods forproducing such compositions and compounds have been discovered. Thepresent compounds have excellent UV light absorbing properties and maybe used in a variety of materials to provide desired UV lightabsorbance. These compounds are particularly useful for incorporation inthe present compositions. The present compositions comprise siliconeelastomer and UV light absorbing component present as, or derived from,one or more of certain UV light absorbing compounds. The present UVlight absorbing compounds are readily soluble in the silicone prepolymeror prepolymers often without heating and/or the use of a co-solvent.Additionally, mixtures of the present UV light absorbing compounds andsilicone prepolymers remain stable, for example, substantiallyhomogenous, over long periods of time, i.e., have long shelf lives, evenat temperatures of less than about 0° C. These features enhance the easeof manufacturing ocular products, such as lenses, from the presentcompositions. Mixtures of the UV light absorbing compound/siliconeprepolymer/cross-linking agent are useful, for example, for producingsolid, cured or cross-linked lens structures for the eye. The presentcompositions can be used to absorb radiation in the wavelength range ofabout 300 nm to about 400 nm. These compositions are preferablyoptically clear and can be utilized for the manufacture of cornealcontact, intraocular and corneal intrastromal lenses. There is nosignificant phase separation, and preferably no significant extraction,of the UV light absorbing component, for example, during normal use ofthe compositions or lenses. The present compounds and compositions canbe made by methods which are very effective and relatively easy andstraight forward to practice.

In one embodiment, the present UV light absorbing compounds comprise UVlight absorbing benzotriazole derivatives having one of the followingstructures or formulas: ##STR1## and mixtures thereof, wherein B is##STR2## each X is independently selected from the group consisting ofH, monovalent hydrocarbon radicals, monovalent substituted hydrocarbonradicals, hydroxyl radicals, amino radicals, carboxyl radicals, alkoxyradicals, substituted alkoxy radicals, and halogen radicals; each R¹ isindependently selected from the group consisting of H and alkylradicals, alkoxy radicals, hydroxyl radicals, amino radicals andcarboxyl radicals; R² is selected from divalent hydrocarbon radicals,divalent substituted hydrocarbon radicals, oxo, divalent oxyhydrocarbonradicals and divalent substituted oxyhydrocarbon radicals; each R³ isindependently selected from alkyl radicals, substituted alkyl radicals,alkoxy radicals, substituted alkoxy radicals, H, alkenyl radicals,substituted alkenyl radicals, R² -B, aryl radicals, substituted arylradicals and fluoro radical; R is selected from R³, H, alkenyl radicalsand substituted alkenyl radicals, alkenoxy and substituted alkenoxyradicals, and acryloxy alkyl and substituted acryloxy alkyl radicals;each R⁴ is independently selected from the group consisting of R and R³,provided that at least one of the R⁴ s is R; c is an integer in therange of 1 to about 10,000; and d is an integer in the range of 0 toabout 100. In one particularly useful embodiment, where the UV lightabsorbing compound is polymerizable, R is selected from H, alkenylradicals and substituted alkenyl radicals, alkenoxy and substitutedalkenoxy radicals, and acryloxy alkyl and substituted acryloxy alkylradicals. If R is other than H, R preferably contains a terminalcarbon-carbon double bond.

The UV light absorbing compositions of the present invention arepreferably optically clear, stable materials useful in the fabricationof corneal contact lenses, corneal intrastromal lenses and intraocularlenses. About 0.05% or 0.1% to about 5% by weight of the UV lightabsorbing component is preferably included in the composition to yieldthe appropriate UV light blocking efficiency, e.g., in samples ofthickness comparable to the final lens products. For example, the UVlight absorbing compositions of the present invention can be formulatedto completely block ultraviolet radiation in the range of about 300 nmto about 390 nm and to display about 2% to about 20% transmittance at400 nm for 0.75 mm thick samples.

The UV light absorbing silicone polymeric compositions substantiallyretain the physical characteristics of the non-UV light absorbingsilicone polymeric compositions. The silicone compositions are such thatthe UV light absorbing component may be covalently attached thereto.Suitable silicone elastomers include, for example, two part platinumcatalyzed, vinyl/hydride, addition cured polysiloxanes, such aspolydimethylsiloxanes, poly dimethyl-diphenyl siloxanes, polymethyl-phenyl siloxanes, and polyorganofluorosiloxanes, as well as otheraddition cured polyorganosiloxanes and the like and mixtures thereof.

The present polymerizable or functional UV light absorbing compounds ormonomers are preferably reacted with hydride or vinyl functionalsiloxane prepolymers and/or with hydride or vinyl functionalcross-linking or cross-linker agents or components to covalently attachthe UV light absorbing component. The cross-linking components arepreferably components of a two-part platinum catalyzed, addition curedsilicone elastomer formulation. The UV light absorbing component ispreferably attached to the prepolymer and/or to a siloxane cross-linkingcomponent by a platinum catalyzed reaction. For example, the UV lightabsorbing monomer may act to form a bridging group similar to that whichforms when the siloxane cross-linking component reacts with the siloxaneprepolymer in the normal curing process to form the silicone elastomer.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to an ultraviolet light absorbingcomposition comprising a silicone elastomer and an effective amount ofUV light absorbing component, which may be physically mixed with and/orcovalently bonded to (and a part of) the silicone elastomer.

The present UV light absorbing compounds, for example, which are the UVlight absorbing components of the present compositions, or from whichthe UV light absorbing components of the present compositions arederived, comprise one or more UV light absorbing benzotriazole compoundshaving one of the following structures or formulas: ##STR3## andmixtures thereof, wherein B is ##STR4## each X is independently selectedfrom the group consisting of H, monovalent hydrocarbon radicals andmonovalent substituted hydrocarbon radicals, preferably containing 1 toabout 8 carbon atoms, hydroxyl radicals, amino radicals, carboxylradicals, alkoxy radicals and substituted alkoxy radicals, preferablycontaining 1 to about 6 carbon atoms, and halogen radicals; each R¹ isindependently selected from the group consisting of H and alkylradicals, substituted alkyl radicals, alkoxy radicals and substitutedalkoxy radicals, preferably containing 1 to about 8, more preferably 1to about 4 carbon atoms, hydroxyl radicals, amino radicals and carboxylradicals; R² is selected from divalent hydrocarbon radicals such asalkylene radicals, divalent substituted hydrocarbon radicals, oxo,divalent oxyhydrocarbon radicals and divalent substituted oxyhydrocarbonradicals, preferably containing up to about 6 carbon atoms and morepreferably containing 1 to about 4 carbon atoms, and still morepreferably being an alkylene radical containing 1 to about 4 carbonatoms; each R³ is independently selected from alkyl radicals,substituted alkyl radicals, alkoxy radicals, substituted alkoxyradicals, H, alkenyl radicals, substituted alkenyl radicals, R² -B, arylradicals, substituted aryl radicals, and fluoro radical, preferably fromalkyl radicals, alkoxy radicals, aryl radicals and R² -B and morepreferably from alkyl radicals, aryl radicals and R² -B; R is selectedfrom R³, H, alkenyl radicals and substituted alkenyl radicals,preferably having 2 to about 6 carbon atoms and more preferably CH=CH₂,alkenoxy and substituted alkenoxy radicals, and acryloxy alkyl andsubstituted acryloxy alkyl radicals; each R⁴ is independently selectedfrom the group consisting of R and R³, provided that at least one of theR⁴ s is R; c is an integer in the range of 1 to about 10,000, preferably1 to about 10 and more preferably 1 to about 4; and d is an integer inthe range of 0 to about 100, preferably 0 to about 10 and morepreferably 0 to about 3. One or more of the R³ s may be organo fluororadicals, for example, fluoro hydrocarbon radicals. In the event the UVlight absorbing compound is polymerizable, R is selected from H, alkenylradicals and substituted alkenyl radicals, alkenoxy and substitutedalkenoxy radicals, and acryloxy alkyl and substituted acryloxy alkylradicals. If R is other than H, R preferably contains a terminalcarbon-carbon double bond.

Preferably, at least one of the Xs and R¹ s is other than H.Particularly useful alkenyl and substituted alkenyl groups from which Ris chosen are those which include a terminal carbon-carbon double bond.In one embodiment, the substituent ortho of the phenolic hydroxyl groupis other than H.

In the event that any R³ is aliphatic, it preferably contains 1 to about8, more preferably 1 to about 4, carbon atoms. If any R³ is aromatic, itpreferably contains 6 to about 10, and more preferably 6, carbon atoms.In a particularly useful embodiment, each R³ is independently selectedfrom methyl radicals, substituted methyl radicals, phenyl radicals andsubstituted phenyl radicals, preferably methyl radicals. In the eventthat an R¹ is alkyl, it is preferably tertiary alkyl, and morepreferably t-butyl.

Examples of useful monovalent hydrocarbon radicals include alkylradicals, alkenyl radicals, aryl radicals and the like. Examples ofuseful alkoxy radicals include methoxy, ethoxy, propoxy, butoxy, hexoxyand the like. A particularly useful halogen group for use as X ischloro. Examples of useful alkyl groups include methyl, ethyl, propyl,butyl, hexyl, octyl and the like. Examples of useful alkenyl radicalsinclude ethenyl (vinyl), propenyl, butenyl, pentenyl, hexenyl, octenyland the like. Examples of useful alkylene groups include ethylene,propylene, butylene and the like. Examples of useful aryl radicalsinclude phenyl, methyl phenyl, ethyl phenyl, dimethyl phenyl and thelike. Examples of useful alkenoxy radicals include ethenoxy, propenoxy,butenoxy, hexenoxy and the like. Examples of useful acryloxy alkylradicals include acryloxy ethyl, acryloxy propyl, acryloxy butyl,acryloxy pentyl and the like.

The substituted groups referred to herein are exemplified by theabove-noted groups (and the other groups referred to herein) substitutedwith one or more substituent groups including elements such as oxygen,nitrogen, carbon, hydrogen, halogen, sulfur, phosphorus and the like andmixtures or combinations thereof. Examples of useful amine groupsinclude -NH₂ and groups in which one or both of the Hs is replaced by agroup selected from monovalent hydrocarbon radicals, monovalentsubstituted hydrocarbon radicals and the like.

In one embodiment, the ultraviolet light absorbing compounds areselected from the group consisting of compounds having the structure (1), noted above, and mixtures thereof. The R² group is preferably bondedto the ortho position or the para position relative to the phenolichydroxyl group of B. In the event R² is bonded to the ortho positionrelative to the phenolic hydroxyl group of B, it is preferred that allof the R¹ s are H.

With further regard to B, it is preferred that no more than one of theXs is other than H, and no more than one of the R¹ s is other than H.That is, it is preferred that all or all but one of the Xs be H, and allor all but one of the R¹ s be H. Such "minimally" substitutedbenzotriazole moieties are relatively easy to produce and provideoutstanding ultraviolet light absorbing properties.

A particularly useful class of UV light absorbing compounds is selectedfrom compounds having the following formula or structure ##STR5##

All tautomers, isomers and the like and mixtures thereof of the presentUV light absorbing compounds are included within the scope of thepresent invention. For example, if R² is an ethylene radical, it may bebonded to the aromatic ring at either the alpha carbon atom or the betacarbon atom. Also, a mixture of such alpha and beta isomers may be usedand is included in the scope of the present invention.

The present hydride functional UV light absorbing compounds can beprepared from functional benzotriazole derivatives which include afunctional group suitable for reacting with a hydride group of asiloxane to covalently bond the siloxane moiety to the benzotriazolemoiety. Examples of useful functional groups which can be included inthe functional benzotriazole derivative include hydroxyl radicals (forexample, hydroxyl-containing monovalent hydrocarbon radicals), alkenylgroups, substituted alkenyl groups and the like. A number of thesefunctional benzotriazole derivatives are well known and/or arecommercially available. Specific examples of useful functionalbenzotriazole derivatives are the vinyl functional benzotriazolederivatives disclosed in Reich et al U.S. Pat. No. 4,868,251 as startingmaterials.

The functional benzotriazole derivative is contacted with a siloxanehaving at least two functional hydride groups if the UV light absorbingcompound is to be polymerizable or with a siloxane having only onefunctional hydride group if a non-polymerizable UV light absorbingcompound is to be produced.

Many of the cyclic hydride-containing siloxane components useful toproduce the ultraviolet light absorbing compounds of structure (2),noted above, are well known. In a particularly useful embodiment, eachof the silicon atoms of such cyclic component has at least one, and morepreferably only one, hydride group directly bonded thereto. A number ofuseful cyclic hydride-containing siloxane component are commerciallyavailable. One especially useful such component istetrahydrotetra-methylcyclotetrasiloxane.

The benzotriazole/siloxane contacting preferably occurs in the liquidphase, using a conventional solvent such as toluene, in the presence ofa catalyst, such as a platinum group metal-containing catalyst, forexample, a platinum-containing catalyst. Contacting conditions aresufficient to allow the functional group of the functional benzotriazolederivative to react with one of the hydride groups (or the onlyfunctional hydride group) of the siloxane. Such conditions can include atemperature in the range of about -600° C. to about 50° C. and reactiontimes in the range of about 1 hour or less to about 60 hours or more.The resulting hydride functional UV light absorbing monomer or monomersor non-polymerizable UV light absorbing compound or compounds can berecovered, separated and/or purified using conventional techniques, suchas distillation, extraction, recrystallization and the like.

The present hydride functional UV light absorbing monomers can be usedto prepare the present unsaturation, for example, vinyl, functional UVlight absorbing monomers. Thus, such hydride functional monomers can becontacted with a functional component selected from the group consistingof compounds containing a plurality of carbon-carbon multiple bonds,such as butadiene, other dienes and the like, compounds containing acarbon-carbon triple bond, such as acetylene, other acetylene-typecompounds and the like, compounds with both a hydroxyl group and acarbon-carbon multiple bond, compounds with an acryloxy alkyl group anda carbon-carbon multiple bond and mixtures thereof. Preferably, thefunctional component includes at least one terminal carbon-carbonmultiple bond. This contacting occurs at conditions effective tochemically react the hydride group of the hydride functionalbenzotriazole derivative with a functional group present in thefunctional component, thereby forming the present unsaturationfunctional monomers which include an R which contains a functionalcarbon-carbon double bond, preferably with a terminal carbon-carbondouble bond.

This contacting preferably occurs in the liquid phase, using aconventional solvent such as toluene, in the presence of a catalyst,such as a platinum group metal-containing catalyst. Contactingconditions are sufficient to allow the hydride group of the hydridefunctional monomer to react with the functional component. Suchconditions can include a temperature in the range of about -60° C. orless to about 50° C. or more and contacting times in the range of about0.2 hours or less to about 10 hours or more. The resulting unsaturationfunctional UV light absorbing monomer or monomers can be recovered,separated and/or purified using conventional techniques, such asdistillation, extraction, recrystallization and the like.

The platinum group metal-containing catalysts or catalyst componentsuseful in the present invention can be selected from any of thecompatible platinum group metal-containing catalysts known to catalyze(or promote) the addition of silicon-bonded hydrogen atoms (hydridegroups) to silicon-bonded vinyl radicals. Such catalyst components canbe any of the known compatible forms, for example, platinic chloride,salts of platinum, chloroplatinic acid and various complexes. A numberof such platinum group metal-containing catalysts are commerciallyavailable. The catalyst component is present in an amount effective topromote the desired reaction. For example, such amount may be sufficientto provide at least about 0.1 ppm by weight (and often no more thanabout 100 ppm by weight) of platinum group metal (calculated aselemental metal) based on the combined weights of the reactantcomponents. In one useful embodiment, the catalyst is chloroplatinicacid complexed with a siloxane such as tetramethylvinylcyclosiloxane(i.e., 1,3,5,7-tetramethyl-1,3,5,7-tetravinyl-cyclosiloxane).

In accordance with one aspect of this invention, new compositions ofmatter comprising one or more UV light absorbing silicone elastomers,for example, UV light absorbing polysiloxanes, preferablypolyorganosiloxane elastomers, are provided. These compositions areprepared by the incorporation of certain UV light absorbing compounds,for example, by the covalent attachment of certain polymerizable UVlight absorbing monomers, as described herein, to silicone materials,preferably to hydride or vinyl functional siloxane base polymers (orpre-polymers) and cross-linking agents or components.

The present compositions preferably further comprise at least onereinforcing agent, such as reinforcing silicone resins, silica and thelike which are conventionally used to strengthen silicone elastomericcompositions. The reinforcing agent or agents are present, if at all, inan amount effective to enhance the strength of the composition relativeto a substantially identical composition without such agent or agents.For example, the reinforcing agent or agents may be present in an amountup to about 50% by weight or more based on the silicone elastomerpresent in the composition.

In one embodiment, the base polymers utilized in the present inventionhave the following structure or formulation: ##STR6## and mixturesthereof, wherein each R⁵ and R⁶ is independently selected from the groupconsisting of H, alkyl radicals, substituted alkyl radicals, alkoxyradicals, substituted alkoxy radicals, alkenyl radicals with a terminaldouble bond, substituted alkenyl radicals with a terminal double bond,aryl radicals, substituted aryl radicals and fluoro radical, providedthat at least one, and preferably at least two, of the R⁵ s is selectedfrom H and olefinically unsaturated groups; and n and m each is aninteger independently selected from integers in the range of 0 to about20,000. In the event that one or more R⁵ s and/or R⁶ s are fluororadicals, one or more other R⁵ s and/or R⁶ s are preferably organicradicals. One or more of the R⁵ s and/or R⁶ s may be organo fluororadicals, for example, fluoro hydrocarbon radicals. In one embodiment,each of the R⁵ s, other than those which are selected from H andolifinically unsaturated groups, and the R⁶ s is methyl. Each of the R⁵s and R⁶ s may be independently selected from alkyl radicals containing1 to about 4 carbon atoms, fluoro alkyl radicals containing 1 to about 3carbon atoms, phenyl radicals, substituted aryl radicals, alkenylradicals containing 2 to about 4 carbon atoms and having a terminaldouble bond and mixtures thereof.

The cross-linking or cross-linker agents useful in the present inventionare preferably components of a two part, silicone elastomer formulation,more preferably a two part, platinum catalyzed vinyl/hydride, additioncured silicone elastomer formulation. In one embodiment, the attachmentof the UV light absorbing monomer to the silicone elastomer preferablyproceeds by a platinum catalyzed reaction to form an ethylenic bridginggroup similar to that which forms when a cross-linking molecule bindstogether siloxane base polymer molecules in the normal curing orcross-linking reaction of the silicone elastomer. Thus, when the basepolymer is vinyl functional, the UV light absorbing monomer can beeither unsaturation functional or hydride functional, preferablyunsaturation functional and more preferably vinyl functional, and thecross-linking agent is hydride functional. Conversely, when the basepolymer is hydride functional, the UV light absorbing monomer can beeither unsaturation functional or hydride functional, preferably hydridefunctional, and the cross-linking agent is vinyl functional. Inaddition, one or more of the base polymer and the cross-linking agentcan be both vinyl and hydride functional.

In any event, the silicone elastomer is cross-linked and opticallyclear, and includes an effective UV light absorbing amount of the UVlight absorbing component of the present invention physically mixedand/or covalently bonded within the silicone elastomer. These opticallyclear, UV light absorbing elastomeric compositions are very effectivefor inclusion in corneal contact lenses, intraocular lenses and cornealintrastromal lenses. Conventional lens forming techniques, for example,molding techniques, can be used to provide lenses comprising the presentUV light absorbing elastomeric compositions.

The preferred siloxane cross-linking agents include a plurality, inparticular at least three (3) of functional groups per molecule. Thus,each cross-linking molecule preferably can participate both in thecovalent attachment of the UV absorbing monomer as well as in theformation of cross-links between siloxane base polymer molecules.

Suitable cross-linking agents include agents which are conventionallyused to produce cross-linked silicone polymers, in particular,polysiloxane elastomers, for example, employing two part platinumcatalyzed silicone systems to produce silicone elastomers byvinyl/hydride addition curing. Thus, suitable cross-linking agents areavailable as a component of many such conventional two part systems.Specific examples of effective cross-linking agents include1,3,5,7-tetramethylcyclotetrasiloxane (i.e.,1,3,5,7-tetramethyl-1,3,5,7-tetrahydrocyclosiloxane),methylhydropolysiloxane,1,3,5-trivinyl-1,1,3,5,5-pentamethyl-trisiloxane, methyl vinylpolysiloxane and the like.

The relative amounts of base polymer, UV light absorbing compound andcross-linking agent employed to produce the final composition, e.g., thesiloxane elastomer composition, are chosen to provide a finalcomposition having the desired properties, including the desired degreeof cross-linking and the desired degree of UV light absorbing ability.The relative amounts of the components utilized varies depending on manyfactors, for example, on the specific components being employed, and onthe application for which the final composition is to be employed. Asnoted above, conventional two part silicone polymer formulations can beemployed. Any adjustments to these conventional formulations (in termsof relative amounts of components) are relatively minor (if required atall) to insure that the relatively minor amount of UV absorbing monomeris effectively incorporated, e.g., physically mixed and/or covalentlyattached, within the final composition.

The incorporation of the UV light absorbing compound can be made tooccur at one or more of various steps in the process of producing an UVlight absorbing silicone elastomer. One method is to simply dissolve theUV light absorbing compound into a mixture of the silicone componentsand to allow the incorporation of the UV light absorbing monomer tooccur simultaneous to the formation of the base polymer cross-links. TheUV light absorbing compound can be combined with the silicone componentsjust prior to the polymerization reaction, for example, at the mixing orinjection head. Also, if desired, the UV absorbing compound can becombined with all or a portion of the silicone components to bepolymerized to form a homogeneous mixture which is stored, for example,for relatively long periods of time, on the order of days or weeks,preferably at reduced temperatures, for example about -80° C. to about0° C., before the polymerization reaction. The presentbenzotriazole-type UV light absorbing compounds have sufficientsolubility so that 1% by weight of a benzotriazole-type UV lightabsorbing compound in accordance with the present invention remains insolution in a curable liquid mixture including all the precursorcomponents of a platinum-catalyzed, cross-linked silicone elastomer evenafter such mixture is maintained for one week at -60° C. This uniquesolubility feature allows silicone compositions to be prepared andstored well in advance of the final polymerization/curing without phaseseparation or precipitation of the UV light absorbing compound, andwithout uneven or premature curing of the mixture. Alternatively, thepresent polymerizable UV light absorbing monomer can be pre-reacted withthe cross-linking agent to form essentially an UV light absorbing,cross-linking adduct. The composite molecule is subsequently formulatedwith siloxane base polymer, and preferably additional platinum catalyst,to be cured into the UV light absorbing silicone elastomer. In anotherembodiment, the present polymerizable UV light absorbing monomer can beintroduced into an already formed (cured) silicone elastomer containingreactable groups, such as an elastomer derived from a two partplatinum-catalyzed hydride/vinyl siloxane monomer mixture. Thepolymerizable UV light absorbing monomer is subjected to conditionseffective to chemically react the reactable UV light absorbing monomerwith the reactable groups of the already formed silicone elastomer. Suchsubjecting is effective to form a polymer material to which iscovalently bonded an UV light absorbing component derived from thepolymerizable UV light absorbing monomer. In any case a degree ofincorporation of the UV light absorbing compound of greater that 95% ispreferably obtained.

The UV light absorbing component covalently attached within the siliconeelastomer does not leach out in aqueous or organic solvents, for exampleisopropanol.

The present UV light absorbing compound often absorbs ultraviolet lightstrongly in the range of about 300 nm to about 400 nm, and exhibitsreduced absorption at wavelengths higher that about 400 nm.

Preferably, the maximum amount of the UV light absorbing compoundincorporated in the UV light absorbing composition of the presentinvention is about 5% by weight. More preferably, the UV light absorbingcompound is incorporated into the UV light absorbing composition in anamount in the range of about 0.05% to about 5% by weight and still morepreferably about 1% or less by weight, especially about 0.1% to about 1%by weight, based on the total composition. Of course, it is understoodthat the present polymerizable UV absorbing monomer is not present assuch in the composition, but is part of the polymer. However, forconvenience and simplicity, in certain instances herein the UV lightabsorbing monomer is referred to as being present in the polymer. Thepercentage of UV light absorbing monomer in the polymer referred toherein means the weight percent of such monomer based on the totalmaterial included in the composition. The amount of UV light absorbingcompound included is that required to give the degree of lightabsorption desired and is dependent, for example, on the specific UVlight absorbing compound or compounds employed, the specific siliconeelastomer producing monomer or monomers employed and on the thickness,e.g., the optical path, of the product, e.g., lens, to be made from thepolymeric composition. By Beers Law of Absorption, the required amountof absorber is inversely proportional to the optical path length throughthe lens device. It is often desired that the ultraviolet lighttransmission at 400 nm be less than about 10 to 15% of the incidentlight and at 390 nm be less than about 3%. The visible lighttransmission in the 410-450 nm range often should not be reduced belowabout 50% of the total light.

As noted above, the present UV light absorbing compounds havesubstantial compatibility with, e.g., solubility in, the base polymersor prepolymers and/or other silicone, in particular siloxane, molecules(e.g., cross-linking agents) used in producing the final siliconeelastomer. Thus, in many instances the UV light absorbing compounds canbe dissolved in the prepolymer/compound mix without using a co-solventand/or without the application of heat. In one embodiment, the presentinvention involves benzotriazole derivatives effective to absorb,preferably preferentially absorb, UV light and having melting pointsless than 25° C. Since a uniform mixture can often be prepared at roomtemperature, that is on the order of about 20° C. to about 25° C., suchmixture can be very conveniently prepared, e.g., at room temperature,without concern for premature and uneven curing, since curing oftenoccurs at relatively elevated temperatures.

The present UV light absorbing compounds can be used very effectively asa component of a curable liquid composition comprising, in addition tothe UV light absorbing compound, a cross-linkable siloxane base polymeror prepolymer, a cross-linking agent, e.g., as described herein, and across-linking catalyst, such as a platinum-containing catalyst asdescribed herein. Such curable liquid composition can be stored atreduced temperature, for example, about -80° C. to about 0° C. for long,on the order of days or weeks, or even indefinite periods of timewithout concern for precipitation or phase separation of the UV lightabsorbing compound, or for uneven or premature curing. The curableliquid composition can be injected into the lens capsule of the eyewhere it is cured at body temperature to a solid, transparent lens whichhas effective UV light absorbing properties. The use of curable liquidcompositions to produce lens structures is disclosed in Wright et alU.S. Pat. No. 4,608,050, which is incorporated in its entirety herein byreference.

The invention will be further described in connection with the followingexamples which are set forth for purposes of illustration only.

The starting material in Example 1 is2-(2'-hydroxy-3'-t-butyl-5'-vinylphenyl)-5-chloro-2H-benzotriazole,hereinafter identified as "I", which itself can be produced as describedin Reich et al U.S. Pat. No. 4,868,251, which is incorporated in itsentirety herein by reference.

EXAMPLE 1

Preparation of 2-[3'-t-butyl-2'-hydroxy-5'-(2"-(7"'-hydro octamethyltetrasiloxane)ethyl) phenyl]-5-chloro-2H-benzotriazole and2-[3'-t-butyl-2'-hydroxy-5'-(1"-7"'-hydrooctamethyltetrasiloxane)ethyl)phenyl]-5-chloro-2H-benzotriazole mixture

The above-noted mixture of the present UV light absorbing monomers isprepared to be used in preparing the mixture of UV light absorbingmonomers in Example 2 and the UV light absorbing silicone composition ofExample 4.

A 100 ml 3 neck flask equipped with a magnetic stirring bar, an inertgas inlet topped reflux condenser and a thermocouple was charged with 20g (0.071 mole) 1,1,3,3,5,5,7,7-octamethyltetrasiloxane (from PetrarchSystems, Inc.), 4.0 g (0.012 mole) of I and 10 g dry toluene. Themixture was stirred at room temperature for 1 hour until all of the Idissolved. 1 ml platinum complex solution (Petrarch Systems, Inc.,catalog no. PC075) was added and the reaction mixture was stirred atroom temperature for 48 hours. Unreacted octamethyltetrasiloxane andtoluene were removed by vacuum. 7.5 g (100%) yellow viscous oil,hereinafter identified as "II" was isolated. Using conventionalchromatography techniques, II can be further purified, if desired.However, this yellow viscous oil, without further purification, iseffective as a polymerizable UV light absorbing monomer mixture. Thismixture remained as a liquid even at -60° C.

Mass spectroscopy analysis indicated a molecular weight for II of 610.High pressure liquid chromatography analysis showed essentially twocomponents corresponding to the IIa (80%) and IIb (20%) isomers, shownbelow. The structures of IIa and IIb isomers and the correspondingconcentration ratio were confirmed by UV/VIS, IR, and ¹ H-NMR analyses.##STR7##

This mixture is found to have very effective UV light absorbingproperties.

EXAMPLE 2

Preparation of a 2-[3'-t-butyl-2'-hydroxy-5'-(2"-(7"'-vinyl octamethyltetrasiloxane) ethyl) phenyl]-5-chloro-2H-benzotriazole and2-[3'-t-butyl-2'-hydroxy-5'- (1"-(7"'-vinyl octamethyl tetrasiloxane)ethyl) phenyl] 5-chloro-2H-benzotriazole mixture

The above-noted mixture of the present UV light absorbing monomers isprepared to be used in preparing the UV light absorbing siliconecomposition of Example 3.

A 100 ml, 3 neck flask equipped with a magnetic stirring bar, a refluxcondenser, an acetylene gas inlet, and a thermocouple was charged with 2g of II (the mixture of isomers) and 60 ml dry toluene. The mixture wasstirred at room temperature for 10 minutes until all II dissolved. Thesolution was purged with dry, scrubbed acetylene gas for 2 hours. 1 mlplatinum complex solution was added. The reaction mixture was stirredand purged with acetylene continuously at room temperature for 6 hours.Unreacted acetylene and toluene were removed by vacuum. 2.0 g (100%)yellow viscous oil, hereinafter identified as "III", was isolated. Usingconventional chromatography techniques, III can be further purified, ifdesired. However, this isolated product is effective as a polymerizableUV light absorbing monomer mixture. This mixture remained as a liquideven at -60° C.

Mass spectrometry analysis indicated a molecular weight for III of 636.High pressure liquid chromatography analysis showed two componentscorresponding to the IIIa (80%) and IIIb (20%) isomers, shown below. Thestructures of the IIIa and IIIb isomers and the correspondingconcentration ratio were confirmed by UV/VIS, IR, and ¹ H-NMR analyses.##STR8##

This mixture is found to have very effective UV light absorbingproperties.

EXAMPLE 3

Preparation of UV Absorbing Silicone

A glass beaker was charged with 10.20 g of part A, and 10.10 g of part Bof a fast cure silicone RTV (McGhan Nusil Corporation Med-6230), and0.066 g of III (the mixture of isomers). The contents were mixedthoroughly with a glass rod at room temperature. The resulting mixturewas deaerated under vacuum and cured at 100° C. for 15 minutes in a moldinto a 0.78 mm thick film. This film was extracted with toluene for 8hours. Both the original film (pre-extraction), which included about0.32% by weight of the UV light absorbing component, and the extractedfilm (post extraction) were optically clear and were tested for UV lightabsorbance.

Results of these tests are as follows:

    ______________________________________                                        % transmission                                                                          0.5%   1.0%   10%   30%  50%  70%   80%                             UV light                                                                      cutoff (nm)                                                                   pre-extraction                                                                          386    388    396   401  405  410   415                             post-extraction                                                                         382    384    393   399  404  409   415                             ______________________________________                                    

These results indicate that both the original film and the extractedfilm have very good UV light absorbing properties. Further, theextracted film showed no significant change in UV light absorbingproperties relative to the film before extraction. The minor differencesin the transmission profiles of the original and purified films mayresult from the use of an unpurified form of the UV light absorbingmonomer and/or the presence of non-reacted, extractable silicones whichare bonded to some of the UV light absorbing monomer and are lost duringextraction.

EXAMPLE 4

Example 3 was repeated using a somewhat larger amount of II (the mixtureof isomers) in place of III. Both the film before extraction, whichincluded 0.54% by weight of the UV light absorbing component and theextracted film were optically clear and were tested for UV lightabsorbance.

Results of these tests were as follows:

    ______________________________________                                        % transmission                                                                          0.5%   1.0%   10%   30%  50%  70%   80%                             UV light                                                                      cutoff (nm)                                                                   pre-extraction                                                                          391    394    400   405  410  415   419                             post-extraction                                                                         389    390    398   403  407  412   417                             ______________________________________                                    

These results indicate that both the original film and the extractedfilm have very good UV light absorbing properties. Further, theextracted film showed no significant change in UV light absorbingproperties relative to the film before extraction.

EXAMPLE 5

Preparation of 2-[3'-t-butyl-2'-hydroxy-5'(2"-heptamethyl trisiloxaneethyl) phenyl]-5-chloro-2H-benzotriazole and2-[3'-t-butyl-2'-hydroxy-5'-(1"-heptamethyltrisiloxane ethyl)phenyl]-5-chloro-2H-benzotriazole mixture

A 100 ml 3 neck flask equipped with a magnetic stirring bar, an inertgas inlet topped reflux condenser and a thermocouple is charged with 20g (0.09 mole ) 1,1,1,3,3,5,5-heptamethyltrisiloxane (Petrarch Systems,Inc.), 4.0 g (0.012 mole) of I and 10 g dry toluene. The mixture isstirred at room temperature for 1 hr until all I dissolved. 1 mlplatinum complex solution (Petrarch Systems, Inc., catalog no. PC-075)is added and the reaction mixture is stirred at room temperature for 48hrs. Unreacted heptamethyltrisiloxane and toluene are removed by vacuum.A yellow viscous oil, hereinafter identified as IV, is isolated usingconventional chromatography techniques, IV can be further purified, ifdesired. However, this yellow viscous oil, without further purificationis effective as a UV light absorbing component. This oil remains aliquid even at -30° C.

Mass spectroscopy analysis indicates a molecular weight for IV of about550. HPLC analysis shows essentially two components corresponding to theIVa and IVb isomers. ##STR9##

This mixture is found to have very effective UV light absorbingproperties.

EXAMPLE 6

Example 3 is repeated using IV (the mixture of isomers) in place of III.The film is extracted with water, instead of toluene, for 8 hours. Boththe film before extraction and the extracted film are optically clearand are tested for UV light absorbance and are found to have very goodUV light absorbing properties.

EXAMPLE 7

Example 1 is repeated except that I is replaced by: ##STR10## After thereaction is completed, the unreacted octamethyltetrasiloxane and tolueneare removed by vacuum to obtain the following compounds: ##STR11##

This material is a yellow transparent liquid. High pressure liquidchromatography analysis shows two compounds corresponding to VIIa (about70%) and VIIB (about 30%) isomers.

EXAMPLE 8

Example 2 is repeated except that II is replaced by the VIIa/VIIbmixture obtained in Example 7. A yellow, transparent viscous liquid isobtained. Conventional high pressure liquid chromatography analysisshows the following isomers to be present. ##STR12##

EXAMPLE 9

Example 1 is repeated except that I is replaced by: ##STR13## A yellow,transparent liquid is obtained. ¹ H-NMR analysis shows the followingcompound to be present: ##STR14##

EXAMPLE 10

Example 2 is repeated except that II is replaced by IXa. A yellowtransparent viscous livid is obtained. ¹ H-NMR analys is shows thefollowing compound to be present: ##STR15##

EXAMPLE 11

Example 10 is repeated except that the acetylene is replaced with1,3-butadiene. A clear, yellow viscous liquid is obtained. ¹ H-NMRanalysis shows the following three compounds to be present: ##STR16##

EXAMPLE 12

Example 1 is repeated except that the 1,1,3,3,5,5,7,7-octamethyltetrasiloxane is replaced with the following cyclic tetrasiloxane:##STR17## A yellow transparent liquid is obtained. High pressure liquidchromatography analysis shows two major components as follows to bepresent: XIIa (about 70%) ##STR18##

EXAMPLE 13

Example 2 is repeated except that II is replaced by the XIIa/XIIbmixture. A yellow viscous liquid is obtained and is found, by ¹ H-NMRanalysis, to include the following compounds: ##STR19##

EXAMPLE 14

Example 1 is repeated except that I is replaced with 12 g of a compoundhaving the following formula: ##STR20## and the1,1,3,3,5,5,7,7-octamethyltetrasiloxane is replaced with 4 g ofpolymethyl hydrosiloxane having the following formula: ##STR21## Atransparent yellow viscous liquid is obtained. The product is identifiedby ¹ H-NMR to have the following formula: ##STR22## where D is XIVa.

EXAMPLE 15

Example 2 is repeated except that II is replaced by XIVc. A yellowviscous oil is obtained. The product is found to have the followingstructure by ¹ H-NMR analysis: ##STR23##

EXAMPLES 16-24

Example 3 is repeated eight (8) times. In each repetition, III isreplaced with a different one of the final products obtained in Examples7 to 15. The UV cutoff of each of the slabs is obtained.

These UV cutoff results indicate that each of these slabs has very goodUV light absorbing properties.

While this invention has been described with respect to various specificexamples and embodiments, it is to be understood that the invention isnot limited thereto and that it can be variously practiced within thescope of the following claims.

What is claimed:
 1. A compound having one of the following formulas##STR24## and mixtures thereof, wherein B is ##STR25## each x isindependently selected from the group consisting of H, monovalenthydrocarbon radicals, monovalent substituted hydrocarbon radicals,hydroxyl radicals, amino radicals, carboxyl radicals, alkoxy radicals,substituted alkoxy radicals, and halogen radicals; each R¹ isindependently selected from the group consisting of H, alkyl radicals,alkoxy radical, hydroxyl radicals, amino radicals and carboxyl radicals;R² is selected from the group consisting of divalent hydrocarbonradicals, divalent substituted hydrocarbon radicals, oxo, divalentoxyhydrocarbon radicals and divalent substituted oxyhydrocarbonradicals; each R³ is independently selected from the group consisting ofalkyl radicals, substituted alkyl radicals, alkoxy radicals, substitutedalkoxy radicals, H, alkenyl radicals, substituted alkenyl radicals, R²-B, aryl radicals, substituted aryl radicals and fluoro radical; R isselected from the group consisting of H, alkenyl radicals andsubstituted alkenyl radicals, alkenoxy radicals, substituted alkenoxyradicals, acryloxy alkyl radicals and substituted acryloxy alkylradicals; each R⁴ is independently selected from the group consisting ofR and R³, provided that at least one of the R⁴ s is R; c is an integerin the range of 1 to about 10,000; and d is an integer in the range of 0to about
 100. 2. The compound of claim 1 wherein each R³ isindependently selected from the group consisting of alkyl radicals andaryl radicals, and said alkenyl radicals and substituted alkenylradicals which contain a terminal carbon-carbon double bond have 2 toabout 6 carbon atoms.
 3. The compound of claim 1 selected from the groupconsisting of compounds having the structure (1) and the mixturesthereof, and R² is bonded to the ortho position or to the para positionrelative to the phenolic hydroxyl group of B.
 4. The compound of claim 3wherein R² is bonded to the ortho position relative to the phenolichydroxyl group of B.
 5. The compound of claim 4 wherein all of the R¹ sare H.
 6. The compound of claim 1 wherein no more than one of the Xs isother than H, no more than one of the R¹ s is other than H, each R³ isindependently selected from the group consisting of alkyl radicalshaving 1 to about 4 carbon atoms, substituted alkyl radicals having 1 toabout 4 carbon atoms, alkoxy radicals having 1 to about 4 carbon atoms,substituted alkoxy radicals having 1 to about 4 carbon atoms, phenylradicals and substituted phenyl radicals.
 7. The compound of claim 1wherein each R³ is a methyl radical and c is an integer in the range of1 to about 4 and d is an integer in the range of 0 to about
 3. 8. Thecompound of claim 1 wherein R² is an alkylene radical.
 9. A compoundhaving the formula ##STR26## wherein B is ##STR27## each x isindependently selected from the group consisting of H, monovalenthydrocarbon radicals, monovalent substituted hydrocarbon radicals,hydroxyl radicals, amino radicals, carboxyl radicals, alkoxy radicals,substituted alkoxy radicals, and halogen radicals; each R¹ isindependently selected from the group consisting of H, alkyl radicals,alkoxy radical, hydroxyl radicals, amino radicals and carboxyl radicals;R² is selected from the group consisting of divalent hydrocarbonradicals, divalent substituted hydrocarbon radicals, oxo, divalentoxyhydrocarbon radicals and divalent substituted oxyhydrocarbonradicals; each R⁴ is independently selected from the group consisting ofalkyl radicals, substituted alkyl radicals, alkoxy radicals, substitutedalkoxy radicals, H, alkenyl radicals, substituted alkenyl radicals, R²-B, aryl radicals, substituted aryl radicals, fluoro radical, alkenoxyradicals, substituted alkenoxy radicals, acryloxy alkyl -radicals andsubstituted acryloxy alkyl radicals, provided that at least one of theR⁴ s is selected from the group consisting of H, alkenyl radicals,substituted alkenyl radicals, alkenoxy radicals, substituted alkenoxyradicals, acryloxy alkyl radicals and substituted acryloxy alkylradicals; and d is an integer in the range of 0 to about
 100. 10. Thecompound of claim 9 wherein said alkenyl radicals and substitutedalkenyl radicals which contain a terminal carbon-carbon double bond have2 to about 6 carbon atoms.
 11. The compound of claim 9 wherein no morethan one of the Xs is other than H, and no more than one of the R¹ s isother than H.
 12. The compound of claim 9 wherein d is an integer in therange of 0 to about
 3. 13. The compound of claim 9 wherein R² is analkylene radical.
 14. A method for producing an ultraviolet lightabsorbing compound comprising:contacting a functional benzotriazolederivative with a siloxane component having at least two functionalhydride groups at conditions effective to chemically react thefunctional group of the benzotriazole derivative with one of the hydridegroups of the siloxane component, thereby forming a hydride functionalbenzotriazole derivative.
 15. The method of claim 14 which furthercomprises contacting said hydride functional benzotriazole derivativewith a functional component selected from the group consisting ofcompounds containing a plurality of carbon-carbon multiple bonds,compounds containing a carbon-carbon triple bond, compounds with both ahydroxyl group and a carbon-carbon multiple bond, compounds with anacryloxy alkyl group and a carbon-carbon multiple bond and mixturesthereof at conditions effective to chemically react the hydride group ofsaid hydride functional benzotriazole derivative with a functional grouppresent in said functional component, thereby forming an unsaturationfunctional benzotriazole derivative.
 16. The method of claim 14 whereinsaid contacting occurs in the presence of a platinum groupmetal-containing catalyst in an amount effective to promote saidchemical reaction.
 17. The method of claim 15 wherein each of saidcontactings occurs in the presence of an effective amount of platinumgroup metal-containing catalyst.